In the Harz and Saxon Switzerland national park regions, the forest has changed considerably in recent years due to prolonged drought and subsequent bark beetle infestation. In keeping with the national park‘s motto “Let nature be nature”, nature is allowed to develop freely in large parts of the national park.

But this regeneration takes time. The sight of dead trees, which takes some getting used to for many visitors, is only a brief stopover on the way to the more species-rich forest of the future. Themed trails at various locations in the national parks illustrate this change with lots of background information.

In the Harz Mountains for example, large areas had to make way for mining and the forests were intensively utilised, especially in the post-war period. Reforestation was carried out in spruce monocultures. The Harz was actually a deciduous forest mountain range and spruce trees only grow there naturally from an altitude of over 700 metres. Similarly, there was a large proportion of monocultures in Saxon Switzerland.

Bark beetles have actually existed in these regions for around 5000 years. However, they were able to spread extremely quickly due to the low tree diversity. The trees are also particularly susceptible due to the storms, heatwaves and drought caused by climate change. The bark beetles can recognise weakened spruce trees by their smell and eat their way under the bark. In doing so, they cut the trees' supply lines, causing them to die.

The fact that the forests are allowed to become wild again is primarily due to the conservation provided by the national parks. Their main task is to protect natural processes. Therefore, they intervene only in a few areas.

For example, dead trees along public transport routes and tourist destinations - including along the route of the Harz narrow-gauge railway - are pulled down or cut back. However, the natural cycle is interrupted as little as possible: the lying and bent trunks resemble the result of a storm.

In order to make the forests less susceptible to the rapid spread of bark beetles, deciduous trees are planted. Due to the spruce monocultures, there are too few deciduous trees for them to seed themselves.  This is why, in the Harz Mountains, for example, 6.4 million deciduous trees were planted between 2008 and 2022.

The national parks do not consider bark beetles as a vermin, but as part of the natural ecosystem. However, to reduce the threat to commercial forests, 500 metre-wide safety strips have been established at the borders of the national park. Bark beetle trees are felled and removed there.